Split detector for fabrics undergoing incremental lateral stretching



Sept. 15, 1970 w, 5, TRQQPE ET AL 3,528,145

SPLIT DETECTOR FOR FABRICS UNDERGOING INCREMENTAL LATERAL STRETCHING Filed Oct. 31 1968 3 Sheets-Sheet l INVENIORS WALTER S. TROOPE CHARLES G. CORP Sept. 15, 1970 w,- 5, TRQOPE ET AL 3,528,145

SPLIT DETECTOR FOR FABRICS UNDERGOING INCREMENTAL LATERAL STRETCHING 3 Sheets-Sheet 2 Filed Oct. 31 1968 FIG. 4

, INVEN'TORS WALTER S. TROOPE CHARLES G. CORP Sept. 15, 1970 Filed Oct. 31, 1968 w. s. TROOPE L SPLIT DETECTOR FOR FABRICS UNDERGOING INCREMENTAL LATERAL STRETCHING :plll

I AAAAA 5 Sheets-Sheet 9 FIG.

l N VEN TORS WALTER S. TROOPE CHARLES G. CORP United States Patent C 3,528,145 SPLIT DETECTOR FOR FABRICS UNDERGOING INCREMENTAL LATERAL STRETCHING Walter S. Troope, Latham, and Charles G. Corp, Mechanicville, N.Y., assignors to Cluett, Peabody & Co., Inc., Troy, N.Y., a corporation of New York Filed Oct. 31, 1968, Ser. No. 772,221 Int. Cl. D06c 3/06 U.S. CI. 2663 7 Claims ABSTRACT OF THE DISCLOSURE This invention is directed to a method and apparatus for stretching and elongating a continuously advancing web of textile fabric transversely to its direction of travel by subjecting it progressively to a multiplicity of simultaneously applied, closely spaced, laterally aligned, sets of stretching forces while simultaneously restraining the selvages against movement toward each other. An ultrasonic scanner is employed to detect and indicate the presence of any fabric splits that may occur. The transverse stretching may be effected either with or without prior or subsequent chemical treatment of the web.

This invention relates generally to new and useful improvements in processes and equipment for treating a continuously advancing fabric web and particularly seeks to provide a novel apparatus for stretching a fabric web transversely to its direction of travel in a multiplicity of closely spaced lateral increments and includes means for detecting any splits that may occur as the result of inadvertently over-stretching the fabric.

It is known, for instance, that losses in the tensile strengths of natural fiber threads and yarns can be reduced by stretching them within predetermined limits; that natural fiber threads and yarns can be more effectively mercerized when under tension or elongation; that the strength of yarns formed from regenerated cellulose can be significantly increased by subjecting them to an elongation on the order of 15% of their original lengths; and that the threads and yarns formed from other synthetic fibers can be similarly treated.

Although it is possible to stretch the threads or yarns in the warp direction of a continuously moving woven fabric web with reasonably uniform results, it heretofore has not been possible to uniformly stretch the threads or yarns of such a moving fabric web in the weft direction.

For example, stretching of the warp threads or yarns may be effected simply by passing the fabric web between the nips of a pair of transverse corrugating rolls or between the nips of two successive closely spaced pairs of draw rolls, the second pair of which is operated at a peripheral speed that is a predetermined amount greater than that of the first pair; thus first imparting an apparent elongation of the warps by temporarily straightening the undulations thereof, then imparting an actual elongation thereto after the undulations have been removed and then relaxing the applied tension to permit the stretched warps to resume their undulating configurations.

Comparable stretching of the weft threads or yarns cannot be effected in the above described manner because they are disposed at a right angle to the warps and thus are not subject to tension applied in the warp direction.

The problem, therefore, is to devise means for applying a controlled and uniform stretch along the full lengths of the wefts as they are being continuously advanced in the warp direction.

Prior efforts to solve this problem as by the use of spreader rolls or bars have been unsuccessful because they operate only over the full width of the fabric web ice with large distances between the points of application of elongation forces of limited effectiveness and thus really serve only to smooth out the fabric.

Other efforts have included devices that move along divergent paths and engage the selvages of the web as it is being advanced to apply a degree of stretch in a direction parallel to the wefts. Here again there are large distances between the points of application of elongation forces and relatively large areas of the fabric are nonuniformly stretched because the tensions are not uniformly applied to each weft yarn and because the yarns themselves are never quite uniform with regard to elongation along their entire length. Also, in this type of operation the edge portions of the web tend to become more greatly stretched than the central portions thereof, which also is undesirable. Furthermore, such processes do not and can not create the high elongation velocities through which the breaking strengths of most fibers may be increased.

The apparatus and process of this invention solve the above stated problem and overcome the deficiencies apparent in prior attempts toward its solution.

It has been discovered that, in order to controllably and uniformly stretch the fabric web as it is being continuously advanced through the apparatus, the elongation forces must be separately and simultaneously applied to the yarns or fibers in a multiplicity of closely spaced lateral zones of small area extending across the full width of the advancing web and in a direction substantially parallel to the axes of such yarns or fibers. Therefore, an object of this invention is to provide an improved process and apparatus for effecting a uniformly controlled stretching of the fabric web as it is being continuously advanced.

Another object of this invention is to provide apparatus of the character stated that includes means for continuously scanning the fabric web as it is discharged from the intermeshed rolls to detect and indicate the linear location of any splits in the fabric that may have been caused during passage of the web through the apparatus.

Another object of this invention is to provide apparatus of the character stated in which the fabric split scanning means includes a transducer for sonically detecting fabric splits as they occur.

With these and other objects, the nature of which will be apparent, the invention will be more fully understood by reference to the drawings, the accompanying detailed description and the appended claims.

In the drawings:

FIG. 1 is a diagrammatic side elevation of apparatus constructed in accordance with this invention;

FIG. 2 is an enlarged end elevation of a portion of the apparatus looking in the direction of the arrows 2-2 in FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view of a portion of the apparatus shown in FIG. 2;

FIG. 4 is a diagrammatic side elevation of a modified form of apparatus provided with an ultrasonic fabric split detector;

FIG. 5 is a perspective view ow the sound reflecting trough and the mountings therefor; and

FIG. 6 is a schematic wiring diagram for the transducer amplifier.

Referring to the drawings in detail it will be seen that the illustrated embodiment of the invention includes a web 10 of fabric that is supplied from a roll 12 arTd initially led over a spreader roll 14 which may be of the so-called scroll roll style having oppositely handed spiral grooves 16- and 18 extending outwardly from the center to the ends thereof. The spreader roll 14 merely smoothes out any Wrinkles in the fabric and does not function to 3 impart any incremental stretching to the fabric within the meaning of this invention.

The web is then threaded into the nip formed by a pair of intermeshing circumferentially grooved rolls 20 and 22, of which the roll 20 is adapted to be driven from a power source (not shown) by a gear 24 afiixed to a roll shaft 26. The roll 22 is mounted for radial adjustment with respect to the roll 20 in order to vary the degree of intermeshing therebetween; and the adjusting means may be either positive as with screw jacks, or yielding as with hydraulic or pneumatic loading cylinders 60 and '61 (as shown on FIG. 2) in the usual manner.

The rolls 20 and 22 respectively include a multiplicity of closely spaced lands 36 and 38 and grooves 40 and 42 which obviosuly are offset in order that the lands of one roll may be received by the grooves of the other roll. Although the contouring of the lands and grooves should be generally curvilinear in order to avoid cutting edges, their exact shapes may be varied within rather wide limits. These lands and grooves enable the fabric to be transversely stretched in a multiplicity of simultaneously applied small zone, small area increments in each of which the weft threads or yarns are uniformly stretched or elongated under controllable conditions. The spacing of the lands (or grooves) preferably should be from about 1 to 3 em, but not over 10 cm., otherwise the benefits derived from the incremental stretching would be adversely affected. This type of stretching might also be referred to as micro-stretching or micro-length stretching meaning simply that the transverse stretching takes place simultaneously over a multiplicity of closely spaced, laterally aligned small increments, zones or areas.

The degree of elongation that can be imparted to the wefts of the Web 10 may be varied by adjusting the spacing between the rolls 20 and 22. In some cases, due to the nature of the fabric being worked, a single pass between the intermeshed rolls is insufficient to produce the full amount of elongation desired. In such instances the web 10, after it leaves the rolls 20 and 22, is led past a second smoothing roll 28 and into the nip between a second pair of intermeshed stretching rolls 30 and 32 to complete the desired transverse elongation, after which it may again be smoothed as by a roll 34 and then Wound into batches or otherwise further processed.

The selvages '46 of the web '10 should be restrained against lateral displacement toward each other as the result of the foreshortening effect created by the intermeshed lands and grooves of the stretching rolls as the web passes through the nip thereof. To this end at least one O-ring 44, formed from rubber or other elastic and resilient material and having a cross-sectional configuration such as to be constantly contacted by an opposing roll land throughout the full range of adjustment between the intermeshed stretching rolls, is fitted into a groove 40 at each end of the roll 20 in a position underlying each selvage 46. The opposing lands 38 of the roll 22 clamp the selvages 46 of the web against the O-ring 44 as the web passes through the roll nip, thus preventing lateral displacement of the selvages while permitting the remainder of the lands and grooves to effect the desired micro-stretching. Obviously, the O-rings 44 will be repositioned whenever a different width fabric is to be worked upon, and will be used at each stage of microstretching if more than one stage is needed.

In normal operation, the degree of intermeshing between the lands and grooves of the stretching rolls should be adjusted to provide either the full amount of desired transverse elongation in a single passage through the nip or a predetermined percentage thereof in a first nip and the balance in one or more subsequent nips. However, in some instances the setting between the stretching rolls may be too close, thus rupturing or splitting the fabric parallel to the direction of web travel by overstretching. Obviously there is a tendency for formation defects in 4 the fabric to rupture at this point. Such a condition might remain undetected for a considerable time and cause the loss of substantial yardage of damaged fabric.

To overcome this problem, and in further accordance with this invention, the apparatus is provided with means for continuously scanning the stretched web as it leaves the nip between the stretching rolls to detect and indicate the linear position in the warp direction of any fabric splits that may occur.

For this purpose (see FIGS. 4-6) the apparatus is equipped with an ultrasconic scanning and detecting unit that includes a pair of 25 Kc. transducers 47, 47 mounted within and at each end of a horizontal metal trough 48 that extends laterally beneath the nip 49 of a pair of intermeshed stretching rolls 50, 50.

The trough 48 is mounted on the outer ends of a pair of spaced parallel arms 51, 51 the inner ends of which are pivotally attached by straps 52 to a frame tie bar 53. The free ends of the arms 51 are provided with a pair of depending legs 54, 54 pivotally attached to a rod 55 extending therebetween. The lower ends of the legs 54 are maintained in a spaced relation by a tie rod 56. The legs 54 normally support the arms 51 in the solid line position shown in FIG. 4 so that the lips of the trough 48 become located within about /2" to 1" from the rolls 50 and the trough can reflect sounds emanating from the fabric leaving the nip.

At startup, the legs 54 are displaced to permit the arms 51 to pivot downwardly to provide adequate clearance between the trough 48 and the rolls 50 for the initial threading of the web through the unit.

In this arrangement the transducers 47, apart from any extraneous background noise, detect the sounds of any fabric splits that may occur and produce a voltage signal which is applied to the input of an amplifier which in turn causes the operation of any or all of the following: a warning signal, a fabric marker or a machine controller. The schematic wiring diagram for a typical amplifier for this purpose is shown in FIG. 6 of the drawings. Amplifiers A, B and C receive the output signal from transducers 47. The amplifiers feed an input signal to transistor D. A rectified output from D is received by transistor E. The output of E in turn operates the appropriate signal device. The resistor G is adjustable to account for background noise levels.

It will be appreciated that, in accordance with the principles of this invention, many different types of fabrics under many different physical and chemical conditions can be controllably micro-stretched transversely to the direction of web travel. For instance, the fabrics could be of all natural fiber, all synthetic fiber or blends of natural and synthetic fibers. The fabrics could be wet or dry and with or without chemical treating materials such as dyes, cross-linking or swelling agents. Obviously, however, the micro-stretching should take place before the fabrics are subjected to any final dimension stabilizing treatment.

For example, a desized, bleached and dyed cotton poplin was dried to 40% moisture at C. and subjected to micro-stretching in accordance with this invention. After treatment, this poplin had a 25% increase of tear strength in the weft direction when compared to a control sample.

As another example, a nylon 6.6 taffeta (56/ 36 threads per cm.) was washed and treated as follows:

(1) Transversely micro-stretched, then dyed under boiling for 1 hour with a dispersion dye including 2% disperse Blue 60 (Color Index Prototype), 4% acetic acid.

(2) Dispersion dyed without transverse micro-stretchmg.

(3) Transversely micro-stretched, then dyed under boiling for 1 hour with an acid dye including 4% acid red (Color Index Prototype), 4% acid.

(4) Acid dyed without transverse micro-stretching.

In each case the micro-stretched fabrics showed a deeper dye affinity than those not so stretched and the acid dyed stretched fabric had fewer streaks than did the acid dyed unstretched fabric.

Although it has been mentioned heretofore that the spacing and contouring of the lands and grooves of the intermeshed stretching rolls (such as 20 and 22) and the degree of intermeshing therebetween must be carefully designed and adjusted to enable the micro-stretching properly to take place, no example has yet been given to indicate how inadvertent overloading of the fabric in the weft direction can cause damaging splits to the fabric parallel to the warps thereof.

For example, if the rolls 20 and 22 of a micro-stretching unit each are assumed to have an outside diameter of a length sufficient to operate on a fabric web 54" wide, and a multiplicity of uniformly curved lands and grooves on 1" centers with a trough to crest depth of 1"; and that the rolls and 22 were operated at a peripheral speed of 35 yards per minute (y.p.m.); and that the amount of intermesh between the lands and grooves is 50% of the trough to crest depth thereof, then if it is further assumed that the above mentioned 36/18 cotton poplin were run through the unit, the 25% increase in tear resistance in the transverse direction would be effected without causing any splits parallel to the direction of web travel.

However, if under the assumed conditions, the amount of intermcsh between the lands and grooves is inadverently or or otherwise increased to say 75% of the trough to crest depth thereof, it is likely that many of the weft threads or yarns would become stretched beyond their breaking points. Small, difficultly detectable splits would occur in a direction parallel to the warps. Such splits are readily detected and indicated by the above described continuously operating ultrasonic scanning unit.

It is of course to be understood that variations in arrangements and proportions of parts as well as substitution of equivalents (such as electronic or other apparati) may be made within the scope of the appended claims.

We claim:

1. Apparatus for transversely stretching a continuously advancing fabric web including, a pair of cylindrical rolls each having a multiplicity of closely spaced circumferential lands and grooves extending along the length thereof said groove spacing from about 1 cm. to 10 cm., means for maintaining said rolls in parallel relationship with the lands and grooves intermeshed whereby to apply simultaneously a multiplicity of closely spaced separate transverse stretching forces across substantially the full with of a fabric web passing through the nips formed between said lands and grooves, means for positively rotating at least one of said rolls, and sonic means for scanning said web after it has been transversely stretched and for detecting the sounds of any fabric splits that may occur.

2. The apparatus of claim 1 in which said scanning and detecting means includes at least one ultrasonic transducer, a signal amplifier electrically connected to said transducer and means for receiving the amplified signal from said amplifier.

3. The apparatus of claim 2 additionally including means for adjusting the position of one of said rolls with respect to the other whereby to vary the degree of intermeshing between the lands and grooves of said rolls.

4. The apparatus of claim 3 additionally including means operably associated with said rolls for preventing the selvages of a fabric web passing through the nip thereof from being drawn laterally toward each other as the intervening portion of the Web becomes trans versely stretched.

5. The apparatus of claim 4 in which said selvage movement preventing means includes at least one elastic O-ring carried within at least one groove of one of said rolls in alignment with each selvage of the fabric web passing thereby, each said O-ring having a cross-sectional dimension and configuration proportioned to assure contact with the opposed land of the opposed roll throughout the full range of land and groove intermeshing relationship therebetween.

6. The apparatus of claim 2 in which said scanning and detecting means additionally includes a sound reflecting trough mounted in proximity to said rolls at the discharge side of the nip therebetween and in parallelism therewith, said transducer being mounted within said trough adjacent one end thereof.

7. The apparatus of claim 4 in which said scanning and detecting means additionally includes a sound reflecting trough mounted in proximity to said rolls at the discharge side of the nip therebetween and in parallelism therewith, said transducer being mounted within said trough adjacent one end thereof.

References Cited UNITED STATES PATENTS 1,696,109 12/1928 Dewhurst 2657 2,752,781 7/1956 Thorsen 73-159 3,164,015 1/196'5 Schafer 73159 US. Cl. X.R. 2670; 73-159 

